传统的变质处理铝硅基合金会引起合金污染等问题，且生产中不可避免地生成有害的针状富铁相，因此迫切需要新方法来解决上述问题。低压交流电脉冲能改善铝硅基合金共晶硅及富铁相的形貌，为控制该类合金凝固过程开辟了新途径。本项目拟以铝硅基多元合金为研究对象，研究低压交流电脉冲对共晶硅形态与富铁相形成的影响及调控机制。首先确定起变质作用的合金元素，揭示其与电脉冲交互作用对共晶硅形核和生长的影响规律，探索元素向共晶硅生长界面附着的动力学，阐明电脉冲下共晶硅的变质机制；探究富铁相的组成、成分和形貌等对脉冲电流参数的响应规律，揭示富铁相形貌转变机制。进而采用定向凝固研究电脉冲下五元铝合金共晶硅和富铁相的生长规律，探明组织的优化工艺参数；结合数值模拟的流场，分析电脉冲对合金元素分布及分凝系数的影响，建立电脉冲下共晶硅和富铁相的生长模型。本项目的研究可为发展先进的电脉冲控制多元合金凝固新技术提供实验指导和理论依据。

Since the addition of a grain refiner and modifier in Al-Si alloys can induce the impurities and undesired particle agglomerates, and the needle-like Fe-intermetallic phase is inevitably produced in industry production, a new approach needs to be proposed for those problems. Recently, we found that the morphology of eutectic silicon phase and Fe-intermetallic phase can be modified by a new low-voltage alternating electric current pulse (LVAECP) technique. It has open up a new way for solidification process of multicomponent Al-Si alloys. In this project, we aim to investigate the effect of a LVAECP on the morphology of eutectic silicon phase and the formation of Fe-intermetallic phase in multicomponent Al-Si alloys and their mechanisms. The alloying element as a function of modifier needs to be determined, and then the effect of alloying elements and LVAECP on the nucleation and growth of eutectic Si is studied. The corresponding mechanism which is related to the intrinsic effects of LVAECP is clarified. The characteristics of microstructure morphology, phase constituents and selected phase for the Fe-intermetallic phase in response to the LVAECP will be studied to reveal the phase transformation kinetics from β-Fe to α-Fe. Furthermore, we study the growth morphologies of eutectic Si and Fe-intermetallic phase in quinary alloys during directional solidification under LVAECP. Combined with the numerical simulation of electromagnetic force and flow field distribution, we analyze the effect of LVAECP on segregation and the effective distribution coefficient of elements. Subsequently, the model of solidification alloys is established under LVAECP, which can promote the development of the solidification theory under LVAECP and provide fundamental principles and technology accumulation for the application of the LVAECP technique.